People often have different preferences and needs concerning light. These needs can be personal e.g. a person might prefer to have certain colours in a light scene. The needs may additionally or alternatively be related to a biological state of the human body e.g. being sleepy, alert, or being in a particular mood that can be affected by light. It is known that exposure to light can influence production of hormone melatonin that regulates sleep-wake rhythm. Studies (Boyce P R. Human Factors in Lighting. 2nd edition, Lighting Research Center, Taylor and Francis group London and New York, 2003) have shown that by exposing people to bright light during the day, their alertness can be increased, but also sleep-wake rhythms can be shifted when exposing people to bright light in the evenings for example for night workers (Bommel W J M van, Beld G J van den. Lighting for work: a review of visual and biological effects. Lighting Res. Technol., 2004. 36: 255-269).
These preferences or needs may be different for individuals living in one household or sharing a space. With the trend of smaller houses the number of users in one space increases enlarging the risk of conflicting preferences.
Connected lighting systems exist that allow a user to control and provide a diverse range of lighting conditions and behaviors within a given space, for example a room. Such systems typically have at least one, often a plurality of, light emitting devices in communication with and controllable via a central lighting control apparatus. The central lighting control apparatus in turn has the ability to accept an input from a user to control the light emitting devices in a network. Some systems have the ability to accept multiple light control inputs from multiple users.
Connected lighting systems may therefore provide a large diversity of light conditions, which increases the likelihood that user input preferences are contradictory.
An example of a connected lighting system is described in Patent document WO2010143089 A1. This document describes systems and methods for automatically deriving and modifying personal preferences applicable to controllable lighting networks. In one aspect the system has an awareness module that detects an identifier for a user, a plurality of adjustments to the at least one controllable lighting network requested by the user, and a context corresponding to each of the plurality of adjustments. An inference engine analyses the plurality of adjustments and the corresponding contexts to identify a correlation between the plurality of adjustments and the contexts, and creates at least one personal preference rule associated with the identifier of the associated user based on the identified correlation. WO2010143089 A1 also describes a method for adjusting a personal preference rule of one user based on criteria of a second user. In this method, a personal preference rule and a first set of criteria are identified for a first user, the personal preference rule having a likelihood value and created based on a correlation between a plurality of adjustments to the controllable lighting network requested by user. Contexts are also identified for the plurality of adjustments. The method also identifies a second set of criteria for at least one second user and compares the first set of criteria with the second set of criteria. The method then adjusts the likelihood value of the personal preference rule based on the comparison and stores the personal preference rule in a preferences database with the user identifier.
Despite such known systems that utilize sets of different criteria to control lighting, peoples lighting needs or preferences may not be a single predefined set of criteria but may vary depending on a number of factors including current physiological state and/or cognitive behavior. Furthermore, new users to the system may not yet have entered any personal preferences or criteria associated with their lighting needs when they enter or are otherwise within a space utilizing a controlled lighting network. Such new users may therefore not have their lighting needs considered by existing lighting systems.